#include <stdio.h>
#include <math.h>

int main() {
    double m, r, i;
    double y;
    
    scanf("%lf %lf %lf", &m, &y, &r);
    
    i = m * (pow(1 + r, y)) - m;
    
    printf("interest = %.2f\n", i);
    
    return 0;
}
